Microprocessors produce heat when operating. The amount of heat is directly proportional to the operating frequency and voltage employed by the microprocessor. Thus, some systems attempt to manage heat production by selectively controlling processor frequency and voltage. The Advanced Configuration and Power Interface (ACPI) standard was produced in part to address challenges associated with thermal management and to facilitate controlling processor frequency and voltage via processor performance states. The ACPI specification facilitates standardizing how an operating system can monitor system usage and/or temperature and then react to various conditions by changing a processor performance state. These processor performance states have typically been available in laptop systems and not in desktop systems.
A processor performance state may specify a frequency and voltage at which a processor is to operate. To facilitate implementing a processor performance state, a processor may include an internal machine specific register (MSR) that can be programmed to control the frequency and voltage associated with a processor performance state. Additionally, a microprocessor may include hardware specifically allocated for an emergency response to an overheated condition. For example, an Intel® Pentium® 4 processor includes a thermal management register (TM2) that can be employed to facilitate controlling temperature. Conventionally, the TM2 register is accessed in response to a processor overheated (PROCHOT) signal being asserted on a line (e.g., PROCHOT line) available to the processor. The PROCHOT signal is typically generated by a thermal management circuit in response to detecting a thermal condition (e.g., overheated). For example, Prior Art FIG. 1 illustrates an example circuit that can be employed to trigger the PROCHOT signal when a processor is overheating.